Exhaust valve seat insert



May 23, 1933. A T, COLWELL 1,911,173

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Patented May 23, 1933 UNITED STATES AIRCHIE T. COLWELL, OF CLEVELANDHEIGHTS, OHIO, ASSIGNOR TO THOMPSON PRODUCTS, INC., OF CLEVELAND, OHIOEXHAUST VALVE SEAT INSERT Application led May- 12,

This invention relates to the art of internal combustion engines .andmore specifically to4 an improved form of valve seat insert for theexhaust valves of the engine.

Heretofore, as is well known, the seats for the exhaust valves of aninternal combustion engine have been formed integrally with the cylinderblock which is a gray iron casting, and hence the seat for the exhaustvalve has m been formed of the same material.

It is also a well known fact that, due to the heat of the exhaust of theengine, the seats of the exhaust valves as well as the valves themselvesare subjected to a comparatively excessive degree of temperature and ithas been found that ordinary gray cast iron (180 to 212 Brinellhardness) used in cylinder blocks will not withstand such excessive heatwithout very objectionable results. The gray 2o iron casting does notpossess sulcient hardness to withstand the eifect of such heat, is notmetallurgically stable at engine-operating temperatures, and is lackingalso in other requirements which are necessary for the highest degree ofeiliciency under such heat condition.

For instance, with excessive engine heat, it has been found that thereis a softening of the cast iron valve seat, and the constant impact 3oof the exhaust valve upon its seat results in distortion of the seat andsinking of the valve into the same. Thus, the valve seat not only losesits true and correct form but yields to such an extent that the valvestem is lowered so as to then constantly ride upon the tappet, and thenormal clearance between the valve stem and the tappet is taken up andthe valve no longer has proper seating engagement.

lVhen the exhaust valve fails to have proper seating engagement, it willbe readily understood that there is no longer obtained proper degree ofcompression of the explosive fuel within the cylinders and, as a result,the temperature is increased by virtue of the fuel being burned ratherthan exploded. Thus, there is a loss of power and there is produced alsoa. lack of uniform compression throughout the cylinders, withtheattendant roughness of operation, difficulty in 5 starting, as wellas other serious disadvan- 'properties and must be capable of flowing1932. Serial No. 610,954.

tages. Such abnormal and ineiicient operation, with over-heating of theengme block as well as the valves themselves, causesalso objectionablescaling and warping of the valves as well as annealing of the valveseats.

An attempt has been made to correct this condition by addingchrome-nickel alloy to the cylinder iron with a resulting increasedhardness of forty 40) or fifty (50) points Brinell, which, however, onlypartially relieves the situation, the valve seat still being distorted.

Attempts have also been made to provide a valve seat constructed as aseparate member and inserted in an annular recess provided about theexhaust valve opening. These attempts have included various compositionsof bronze as well as steel, but all of them are open to certainobjections due either to their failure to meet the necessaryrequirements of operation or to their excessive high costof production.

In order to meet the necessary requirements for successful operation,the metal adopted for such an insert must possessv I5 hardeningproperties and must possess suficiently high physical hardness to resistdistortion and deformation from the hammering action of the valve. Suchan exhaust valve seat insert must also possess a very high degree ofstable hardness under red heat corresponding to the excessive heatdeveloped by the engine under extreme conditions. Also, such a seatinsert must have substantially the same co-eiiicient of expansion as thecast-iron of the block itself into which the insertis placed.Furthermore, the insert must be proof against softening, tempering, orchange in volume under the extreme temperature to which subjected duringactual use; and the composition of metal selected for such an insertmust be proof against scaling and warping as Well as againstdisintegration or segregation of the constituent elements under theheating and cooling conditions of the engine, and must be uniformly andconstantly homogeneous under all such varying conditions. Also, such acomposition of metal must possess good casting properly at castingtemperatures so that such inserts can be formed eiliciently inindividual molds, and must be pioof against any tendency toward porosityor the formation of blow-holes. Finally, the cost of the constituentelements in raw state must be comparatively low and such materials mustbe readily available so as to render it feasible and practical tomanufacture such form of insert in quantity production for the market.

lVith these necessary requirements in mind, I have found that nearly allof the former attempts at a separate forni of insert are altogetherimpractical since they lack the necessary physical requirements forsuccessful and satisfactory perfoi'inance in the several respectsalready mentioned. In View of these considerations, the field ofselection of a material which could be depended upon for successfuloperation has been liml ited to a certain class of steel, for instancehigh speed steel, which, however, has proved to be not at all practicalas a marketable product because of its high cost and for other reasons.

Moreover, in the actual manufacture of such inserts from the compositionof steel just mentioned, there has been followed the practice of forgingthe inserts in the form of rings from the end of bar stock by thesuccessive operations of piercing, expanding, and shearing 0E the ringin an attempt to avoid the Waste of material. However, the final cost ofsuch a product constructed from such material and in such a manner isentirely too high for practical purposes.

Therefore, the object of the present invention is to devise an improvedcomposition of metal for an insert which may be adopted for the purposeherein stated and which will not only fulfill all of the variousrequirements from the standpoint of efficient operation but which mayalso be manufactured and s old at a comparatively low cost, and theconstituent elements of which are readily available for suchmanufacture.

More specifically, it is the obj ect of the present invention to devisean exhaust valve seat insert in the form of a semi-steel castingcomprising an alloy of constituent elements which are readily availableupon the market at a comparatively low cost and which will produce aninsert having substantially. the same co-eiiieient of expansion as thegray iron of the engine block, and which will withstand the excessiveheat of the engine and will also A possess all of the requisitecharacteristics and none of the objectionable features, as abovementioned.

Other objects will appear from the following description and claims.

Fig. l is a sectional view of a portionof the block of an internalcombustion engine and illustrates an exhaust valve seat in the form ofan insert;

Fig. 2 is a perspective View of such an insert;

Fig. 3 is a top plan view of the saine; and

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3.

Referring to the accompanying drawing, the engine block is indicated byreference numeral l, the exhaust val've is indicated by referencenumeral 2, and the valve seat which, according to the present inventionis in the form of an insert, is indicated by reference numeral 3. Thisinsert is beveled at 3 so as to provide the proper form of seat forengagement by the exhaust valve in the usual manner. Such insert is inthe form of a closed ring, as clearly indicated in the drawing, and isinserted in any suitable manner into an annular recess providediaboutthe end of each exhaust opening.

As above explained, there have already been attempts to provide exhaustvalve seats in the form of inserts and the present form of illustrationis therefore intended to indicate this same general combination ofinsert in the engine block. The novelty in the present case, as willmore fully appear hereinafter, consists in the specilic composition ofalloy adopted in the insert itself, and consists also in the combinationof this particular metallic composition of insert and the block itselfby virtue of the peculiar co-relation between my present improved alloyand the gray iron of the block casting.

As a means of accomplishing the desired results in the present case, Ihave discovered several forms of alloys which may be adopted for use inthe insert forni of exhaust valve seat, and all of which are capable ofproducing the satisfactory results as herein specified. It is to beunderstood that the present disclosure may be varied within the range ofequivalents so far as the selection of specific elements is concernedand also within the range of various relative proportions as may bedictated or discovered by actual experimentation, all in accordance withthe principle of invention as herein set forth.

Accordingly, I have below indicated several different combinations ofelements with several alternatives and have also indicated approximateranges of percentage composition of the several alloys. Therefore, it isto be understood that the scope of the pieseiit invention is not limitedexactly to any particular specimen herein set forth, either with respectto the elements themselves or the percentage composition. As a means ofconvenience in the claims, I have referred to the percentages and rangesas being approximate so as to afford suitable scope of protection.

One specific composition of semi-steel casting which has by actual testproved satisfactory in fulfilling all of the exacting requirementsherein specified for such an insert, was found by actual analysis to beas follows, the percentages given being by Remainder principally iron.

This alloy was heat-treated by subjecting the same to approximatelytwelve hundred degrees (l200) Fahrenheit, this degree'l of heat being inexcess of that to which the ring would ordinarily be subjected duringactual use under extreme heat conditions in an internal combustionengine, and the ring 1nsert was formedas a semi-casting which Was theninished by grinding and provided with the usual form of bevel seat 3a.

This form of ring may be inserted into place, as indicated in Fig. 1 ofthe drawing, in any suitable and well known manner.

As already stated, it is to be understood that the above specificcomposition of semisteel casting is intended to illustrate only oneparticular alloy which may be employed 'for this purpose. The percentagecomposition of this alloy may be varied, approximately within thefollowing ranges, these percentages being by weight:

i Percent Carbon .50 to 3.50 Molybdenum or tungsten .50 to 10.00Chromium .50 to 10.00 Silicon .50 to 3.00

Remainder principally iron.

Other modified forms of alloys with the approximate range of percentagecomposition (by weight) of the constituent elements, will now beindicated:

Remainder principally iron.

Thus, I have devised an insert form of ring seat for the exhaust valveof an internal combustion engine which possesses all of the desiredadvantages as above enumerated and which is free of the features whichheretofore have proved objectionable and which made the insert form ofseat wholly impractical. With my improved form of. insert,

lnot only is the. life of the valve seat itself doubled or trebled ascompared with the old form of seat which was integral with and thereforeof the same metalhc composition as the gray iron casting of the block,ut also there is herein obtained a correspondin increase in theefficiency of operation o the engine because of the improved conditionsas regards certain vital factors and considerations above explained andas will be readily understood by those who are familiar with the art ofinternal combustion engines.

Furthermore, the composition of metal herein adopted is one which may beproduced at a comparatively low cost and is therefore rendered practicalfor adoption in all popular forms of automobile engines, and theconstituent elements of thecomposition of metal herein disclosed may bereadily obtained for such use.

What I claim is:

1. In an internal combustion engine, the combination of a cast-ironengine block having exhaust valve openings and having a cutout portionabout the upper end of each exhaust valve opening so as to form anannular seat, and a separately formed valve seat member inserted in eachannular seat and adapted for seating engagement by the exhaust valve,said valve seat insert being in the form of a semi-steel castingincluding carbon, a metal of the molybdenum-tungsten group, chromium,and silicon, the remainder being principally iron.

2. In an internal combustion engine, the combination of a cast-ironengine block having exhaust valve openings and having a cutout portionabout the upper end of each exhaust valve opening so as to form anannular seat, and a separately formed valve seat member inserted in saidannular seat and adapted for seating engagement by the exhaust valve,said valve seat insert being in the form of a semi-steel castingincluding approximately from one-half of yone per cent (.50%) to threeand one-half per cent (3.50%) by weight of carbon, approximatelyone-half of one per cent to ten per cent (10.00%) by welght of a metalof the molybdenumtungsten group, approximately fromonehalf of one per.cent (50%) to ten per cent (10.00%) by weight of chromium, andapproximately from one-half of one per cent (.50%) to three per cent(3.00%) by weight of silicon, the remainder being principally iron.

3. In an internal combustion engine, the combination of a cast-ironengine block having exhaust valve openings and having a cut-out portionabout the upper end of each exhaust valve opening so as to form anannular seat, and a separately formed valve seat member inserted in eachannular seat and adapted for seating engagement by the exhaust valve,said valve seat insert being in the form of a semi-steel castingincluding approximately two per cent (2.00%) by Weight of carbon,approximately tive per cent (5.00%) by Weight of a metal of themolybdemini-tungsten group, approximately three per cent (3.00%) byweight ot chromium, and approximately one and one-fourth per cent(1.25%) by weight of silicon, the remainder being principally iron.

4. In an internal combustion engine, a valve seat insert adapted forseating engagement by the exhaust valve and being in the form of asemi-steel casting, comprising approximately from one-half of one percent (.50%) to three and one-half per Cent 3.50 by weight of carbon,approximately from one-half of one per cent (50%) to ten per cent(10.00%) by weight of a metal of4 the molybdenum-tungsten group,approximately from one-half ofone per cent (.50%) to ten per cent(10.00%) by weight of chromium, and approximately one-halt of one percent (50%) to -three per cent (3.00%) by weight of silicon the remainderbeing principally iron, said valve seat insert being preliminarilyheat-treated to a degree corresponding at least to excessive engineheat.

5. In an internal combustion engine, an exhaust valve seat insertadapted for seating engagement bythe exhaust valve and being in the formof a semi-steel casting, comprising approximately two per cent (2.00%)by Weight of carbon, approximately live per cent (5.00%) by Weight of ametal of the molybdenum-tungsten group, approximately three per cent(3.00%) by Weight of chromium, and approximately one and one-fourth pereent (1.25%) by Weight of silicon the remainder being principally iron,said valve seat insert being preliminarily heat-treated to approximatelytwelve hundred degrees (12000) Fahrenheit.

6. In an internal combustion engine, a valve seat insert adapted forseating engagement by the exhaust valvel and being in the form of asemi-steel casting, comprising approximately from one-half of onepercent (50%) to three and one-half per cent (3.50%) by Weight of carbon,approximately from one-half of one per cent (.50%) to ten signature.

ARCHIE T. COIIWELL.

per cent (10.00%) by weight of aY metal of` the molybdenum-tungstengroup and approximately from one-half of one per cent (50%) to three percent (3.00%) by Weight of silicon. the remainder being principally iron.said valve seat insert being preliminarily heat-treated to a degreecorresponding at least to excessive engine heat and having substantiallythe same coefficient of expansion as Cast iron.

7. In an internal combustion engine, a valve seat insert adapted forseating engagement by the exhaust valve and being in the form of asemi-steel casting, comprising approximately from one-half of one percent (50%) by Weight of carbon, approximately

